Quarter	Percent
1998-01-01	71.2
1998-04-01	71
1998-07-01	70.7
1998-10-01	70.9
1999-01-01	71.4
1999-04-01	71.1
1999-07-01	70.6
1999-10-01	70.8
2000-01-01	71.8
2000-04-01	71.4
2000-07-01	70.6
2000-10-01	70.5
2001-01-01	71.2
2001-04-01	71.8
2001-07-01	70.4
2001-10-01	69.8
2002-01-01	70.5
2002-04-01	70.1
2002-07-01	69.5
2002-10-01	69.3
2003-01-01	69.6
2003-04-01	68.7
2003-07-01	68.2
2003-10-01	67.7
2004-01-01	69.5
2004-04-01	68.5
2004-07-01	67.6
2004-10-01	66.9
2005-01-01	67.8
2005-04-01	67.7
2005-07-01	67.6
2005-10-01	66.6
2006-01-01	67.5
2006-04-01	66.6
2006-07-01	66.1
2006-10-01	66.2
2007-01-01	66.2
2007-04-01	65.3
2007-07-01	65
2007-10-01	65.5
2008-01-01	65.8
2008-04-01	64.2
2008-07-01	64.1
2008-10-01	64.2
2009-01-01	63.8
2009-04-01	62.5
2009-07-01	63.2
2009-10-01	62.9
2010-01-01	62.4
2010-04-01	62.2
2010-07-01	62.3
2010-10-01	61.6
2011-01-01	61.2
2011-04-01	61.3
2011-07-01	60.8
2011-10-01	59.3
2012-01-01	58.8
2012-04-01	57.4
2012-07-01	57.2
2012-10-01	56.5
2013-01-01	56.3
2013-04-01	55.5
2013-07-01	54.2
2013-10-01	53
2014-01-01	52.4
2014-04-01	51.5
2014-07-01	50.5
2014-10-01	49.9
2015-01-01	49.6
2015-04-01	48.6
2015-07-01	48.9
2015-10-01	48.7
2016-01-01	47.6
2016-04-01	46.3
2016-07-01	46.6
2016-10-01	45.9
2017-01-01	45.5
2017-04-01	44.6
2017-07-01	44.5
2017-10-01	43.7
2018-01-01	43.6
2018-04-01	42.6